Inerbaev Talgat M, Graupner David R, Abuova Aisulu U, Abuova Fatima U, Kilin Dmitri S
L.N. Gumilyov Eurasian National University Astana 010000 Kazakhstan
Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Science 119991 Moscow Russia.
RSC Adv. 2025 Feb 18;15(7):5405-5412. doi: 10.1039/d4ra06938b. eCollection 2025 Feb 13.
The optical properties of the tetragonal phase of BaTiO have been studied using the density functional method. In the study of a static lattice, we employed the generalized gradient approximation functional combined with on-site Hubbard correlation (GGA + ) and a hybrid functional. To account for the thermal motion of the atoms, we performed molecular dynamics calculations using the GGA + method. We calculated the optical absorption spectra both for the static lattice and along the molecular dynamics trajectory. The results show that considering the motion of atoms leads to a significant decrease in the calculated value of the threshold energy for optical absorption. This effect occurs for two main reasons. First, changes in the atomic configuration due to thermal motion make electronic transitions that were previously dark for a static lattice become bright. Second, the optical absorption threshold decreases due to fluctuations in the energy of electronic transitions caused by the motion of atoms. The calculations were performed separately for different -points of the Brillouin zone. The dispersion of electron energy in the reciprocal space may explain some features observed in the photoluminescence spectra.
利用密度泛函方法研究了BaTiO四方相的光学性质。在静态晶格研究中，我们采用了广义梯度近似泛函结合在位哈伯德关联（GGA + ）和混合泛函。为了考虑原子的热运动，我们使用GGA + 方法进行了分子动力学计算。我们计算了静态晶格以及沿着分子动力学轨迹的光吸收光谱。结果表明，考虑原子运动导致光吸收阈值能量的计算值显著降低。这种效应主要有两个原因。首先，热运动引起的原子构型变化使静态晶格中原本暗的电子跃迁变亮。其次，由于原子运动引起的电子跃迁能量波动，光吸收阈值降低。计算是在布里渊区的不同点分别进行的。倒易空间中电子能量的色散可以解释光致发光光谱中观察到的一些特征。
